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188 Hardware Reference Manual
Intel
®
IXP2800 Network Processor
DRAM
5.2 Size Configuration
Each channel can be populated with 1 – 4 RDRAMs (Short Channel Mode). For supported loading
configurations, refer to Table 61. The RAM technology used determines the increment size and
maximum memory per channel as shown in Table 62.
Note: One or two channels can be left unpopulated if desired.
RDRAMs with 1 x 16 dependent banks, 2 x 16 dependent banks, and four independent banks are
supported.
Table 61. RDRAM Loading
Bus Interface Maximum Number of Loads Trace Length (inches)
Short Channel: 400 and 533 MHz 4 devices per channel. 20
1
1. For termination, the DRAMs should be located as close as possible to the IXP2800 Network Processor.
Long Channel: 400 MHz
2 RIMMs per channel – a maximum of
32 devices in both RIMMs.
20
1
Long Channel: 533 MHz
1 RIMM and 1 C-RIMM per channel –
a maximum of 16 devices.
20
1
Table 62. RDRAM Sizes
RDRAM Technology
1
Increment Size Maximum per Channel
64/72 MB 8 MBs 256 MB
128/144 MB 16 MB 512 MB
256/288 MB 32 MB 1 GB
2
512/576 MB 64 MB 2 GB
2
NOTES:
1. The two numbers shown for each technology indicate x16 parts and x18 parts.
2. The maximum memory that can be addressed across all channels is 2 Gbytes. This limitation is based on
the partitioning of the 4-Gbyte address space (32-bit addresses). Therefore, if all three channels are used,
each can be populated up to a maximum of 768 Mbytes. Two channels can be populated to a maximum of
1 Gbyte each. A single channel could be populated to a maximum of 1 Gbyte.